1. Field of the Invention
The present invention relates to a manufacturing method of a substrate provided with a semiconductor layer with an insulating film interposed therebetween, particularly, a silicon-on-insulator (SOI) substrate.
2. Description of the Related Art
In recent years, integrated circuits that use a silicon on insulator (SOI) substrate in which a thin single crystal semiconductor layer is provided on an insulating surface, instead of a bulk silicon wafer, have been developed. By utilizing characteristics of a thin single crystal silicon film formed over an insulating film, transistors formed in the integrated circuit can be separated from each other completely. Further, since fully-depleted transistors can be formed, a semiconductor integrated circuit with high added value such as high integration, high speed driving, and low power consumption can be realized.
As one of the manufacturing methods of SOI substrates, a Smart Cut (registered trademark) method can be given. By a Smart Cut (registered trademark) method, not only an SOI substrate in which a single crystal silicon film is formed over a silicon substrate but also an SOI substrate in which a single crystal silicon film is formed over an insulating substrate such as a glass substrate can be manufactured (for example, see Patent Document 1). A manufacturing method of an SOI substrate having a single crystal silicon thin film over a glass substrate, in which a Smart Cut (registered trademark) method is used, is briefly described below. First, a silicon dioxide film is formed over a surface of a single crystal silicon wafer. Next, by implantation of a hydrogen ion into the single crystal silicon wafer, a hydrogen ion implantation plane is formed at a predetermined depth in the single crystal silicon wafer. Then, the single crystal silicon wafer into which the hydrogen ion is implanted is bonded to a glass substrate with the silicon dioxide film interposed therebetween. After that, a heat treatment is performed, whereby the hydrogen ion implantation plane serves as a cleavage plane and a thin film of the single crystal silicon wafer into which the hydrogen ion is implanted is separated. In this manner, a single crystal silicon thin film can be formed over the bonded glass substrate. This Smart Cut (registered trademark) method may also be referred to as a hydrogen ion implantation separation method.